1. Field of the Invention
The present invention relates to a method and a device for determining the absolute position of a component, especially the absolute position of a flap for controlling fluid flows in an internal combustion engine.
2. Description of Related Art
Various flaps are provided in an internal combustion engine for controlling fluid flows. A charge movement flap may, for instance, be situated in the intake tract, shortly before the intake valve, in order to increase the turbulence of the flow in the combustion chamber, and thus to improve the thorough mixing of the air/fuel mixture. An intake-manifold switchover flap may also be provided, by which the effective length of an intake manifold is able to be changed. These flaps are usually driven by an electric motor and a gear unit, and are mostly just moved back and forth from end position to end position.
Up to now, the position of such flaps has been either controlled or regulated. In the control of the flaps, on the one hand, an external sensor may be provided for diagnosis. If no external sensor is provided, no diagnosis can be performed. Alternatively, the functioning of the flap may be diagnosed via external sensors and regulated.
In one usual control of such a flap, in the case of a construction in which no external sensor is provided, the flap may be moved to its end position at a predetermined tilting speed, for example. The flap then strikes against the limiting stop at the tilting speed, whereby the flap itself, or particularly a gear unit with which the flap is coupled to a drive, is greatly stressed. This leads to increased wear or damage to the flap or to its drive. Alternatively, the tilting speed may be kept so low over the entire adjusting path of the flap that no forceful impact is able to take place at the limiting stop. However, the adjusting time of the flap becomes considerably longer, because of this. To be sure, this problem may be solved by control or regulation of the flap using external position sensors, but if that is so, additional components have to be provided, installed and maintained.